Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2009	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Received refund from the IRS	$ 40,418us-gaap_ProceedsFromIncomeTaxRefunds
Taxes owed		$ 5,300

The amount of cash received during the period as refunds for the overpayment of taxes.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

Name:	us-gaap_ProceedsFromIncomeTaxRefunds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration